This invention relates to display systems.
More particularly the invention relates to display systems of the kind utilising a display device for producing a display of raster scan format; a storage means having an array of storage locations, each location being adapted to contain data representing a visual parameter of a different pixel of a picture to be displayed by the display device; and signal generating means for applying to the display device a signal in which successive portions respectively represent data stored in different locations of the storage device, the sequence of the data in said signal corresponding to the raster scan format of the display picture.
In such a system the data is normally stored in the storage means in a configuration corresponding to the format of the displayed picture so that there is a one-to-one positional correspondence between the storage locations and the pixels of the displayed picture.
In some applications of such a display system, e.g. in a vehicle moving map display system, the picture to be displayed by the system is part of a larger picture and it is required that the portion of the larger picture which is displayed is slightly changed from time to time.
Thus in a vehicle moving map display system, a portion of a large map is displayed and the displayed portion of the large map is required to change progressively with vehicle movement.
Where there is a one-to-one positional correspondence between each storage location and the pixels of the displayed image, for each such change in the displayed picture the data in each storage location of the storage device has to be changed, and it is not practicable to change the data sufficiently quickly to produce a smoothly moving display.